In motor vehicle engineering, brake-by-wire brake systems are becoming ever more widespread. Such brake systems often include not only a master brake cylinder which can be actuated by the vehicle driver but also an electrically controllable pressure supply device by means of which the wheel brakes are actuated in the brake-by-wire operating mode.
International patent application WO 2013/023953 A1 discloses a brake actuation unit for a brake-by-wire motor vehicle brake system. In this context, arranged in the unit are a brake-pedal actuatable master brake cylinder to which the wheel brakes of the motor vehicle can be connected, an electrically controllable pressure supply device which is embodied as a hydraulic cylinder-piston arrangement whose piston can be moved by an electric motor by means of a rotation-translation gear mechanism, a brake pedal sensation simulator, a valve arrangement and an electronic open-loop and closed-loop control unit (referred to as a one-box design). The wheel brakes are supplied with pressure by the pressure supply device in a brake-by-wire operating mode. A pressure buildup by the pressure supply device is no longer possible even in the case of a single fault in the region of the pressure supply device, in particular a leak in the seal of the pressure space of the pressure supply device or a fault in the electrical activation of the electric motor of the pressure supply device, and the wheel brakes can then only be supplied with pressure by the vehicle driver by means of the master brake cylinder. Owing to this restricted availability of the brake actuation unit, such an actuation unit is therefore not suitable for partially autonomous or autonomous driving.
The object of the present invention is to make available a brake system with which the safety requirements of partially autonomous or autonomous driving are satisfied. In this context, for reasons of costs and installation space, an integrated brake actuation unit (one-box design) with only one electrically activatable pressure supply device and only one electronic open-loop and closed-loop control unit for activating the brake actuation unit is to be adhered to, in particular the pressure supply device and the valve arrangement are to be adhered to.
This object is achieved according to the invention by means of a brake actuation unit as described herein.